WO 96/16714 discloses a container for separating a blood or plasma components, e.g., fibrin monomer, from blood or plasma by a centrifugation about a vertical axis. This container comprises a first annular chamber defined by an outer cylindrical wall and an inner cylindrical wall, both walls extending coaxially about a common axis, as well as by a top wall and a bottom wall, where the bottom wall is formed by a piston displaceable within the first chamber. The container further comprises a second chamber accommodated below the first chamber and communicating with the first chamber through a first conduit. The second chamber is defined by the outer cylindrical wall, the bottom wall of the first chamber, and by a second bottom wall. This second chamber serves as reaction chamber for receiving plasma and treating the plasma to obtain the desired component. For example, treatment of plasma fibrinogen with thrombin or a thrombin-like enzyme converts the fibrinogen to fibrin monomer which spontaneously polymerizes to a non-crosslinked fibrin polymer. Placing this container in a centrifuge for the above-described reaction provides that the non-crosslinked fibrin polymer is separated from the plasma and deposited on an outer wall of the reaction chamber during centrifugation. When the piston is subsequently actuated, the remaining plasma is removed from the reaction chamber. Thereafter, a solvent is added for dissolving the so-deposited non-crosslinked fibrin polymer and forming the desired fibrin monomer solution. As described in detail in EP 592242 this fibrin monomer solution is extremely useful, for example, in fibrin sealant methods. It is desirable to use devices like those described in U.S. Pat. No. 5,603,845, WO 96/16713, WO 96/16714 and WO 96/16715 to prepare blood products such as fibrin sealant components immediately at the time of surgery so that autologous blood can be utilized. It may also be desirable from a surgeon's perspective to use sealant products which are relatively uniform from one procedure to another. This is nearly impossible for freshly prepared products, however, since fibrinogen concentration in human blood can vary by .+-.300% in human patient populations and freshly prepared sealant components from individual sources will also vary. Most humans have fibrinogen levels between 2 and 6 mg/ml of plasma and some humans may have as little as 1 mg/ml and some as much as 10 mg/ml (fibrinogen plasma).